A microRNA expression signature of human solid tumors defines cancer gene targets

Small noncoding microRNAs (miRNAs) can contribute to cancer development and progression and are differentially expressed in normal tissues and cancers. From a large-scale miRnome analysis on 540 samples including lung, breast, stomach, prostate, colon, and pancreatic tumors, we identified a solid cancer miRNA signature composed by a large portion of overexpressed miRNAs. Among these miRNAs are some with well characterized cancer association, such as miR-17-5p, miR-20a, miR-21, miR-92, miR-106a, and miR-155. The predicted targets for the differentially expressed miRNAs are significantly enriched for protein-coding tumor suppressors and oncogenes (P < 0.0001). A number of the predicted targets, including the tumor suppressors RB1 (Retinoblastoma 1) and TGFBR2 (transforming growth factor, beta receptor II) genes were confirmed experimentally. Our results indicate that miRNAs are extensively involved in cancer pathogenesis of solid tumors and support their function as either dominant or recessive cancer genes.

MicroRNA gene expression deregulation in human breast cancer

MicroRNAs (miRNAs) are a class of small noncoding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. Their aberrant expression may be involved in human diseases, including cancer. Indeed, miRNA aberrant expression has been previously found in human chronic lymphocytic leukemias, where miRNA signatures were associated with specific clinicobiological features. Here, we show that, compared with normal breast tissue, miRNAs are also aberrantly expressed in human breast cancer. The overall miRNA expression could clearly separate normal versus cancer tissues, with the most significantly deregulated miRNAs being mir-125b, mir-145, mir-21, and mir-155. Results were confirmed by microarray and Northern blot analyses. We could identify miRNAs whose expression was correlated with specific breast cancer biopathologic features, such as estrogen and progesterone receptor expression, tumor stage, vascular invasion, or proliferation index.

miR-15 and miR-16 induce apoptosis by targeting BCL2

Chronic lymphocytic leukemia (CLL) is the most common human leukemia and is characterized by predominantly nondividing malignant B cells overexpressing the antiapoptotic B cell lymphoma 2 (Bcl2) protein. miR-15a and miR-16-1 are deleted or down-regulated in the majority of CLLs. Here, we demonstrate that miR-15a and miR-16-1 expression is inversely correlated to Bcl2 expression in CLL and that both microRNAs negatively regulate Bcl2 at a posttranscriptional level. BCL2 repression by these microRNAs induces apoptopsis in a leukemic cell line model. Therefore, miR-15 and miR-16 are natural antisense Bcl2 interactors that could be used for therapy of Bcl2-overexpressing tumors.

A MicroRNA signature associated with prognosis and progression in chronic lymphocytic leukemia

BACKGROUND

MicroRNA expression profiles can be used to distinguish normal B cells from malignant B cells in patients with chronic lymphocytic leukemia (CLL). We investigated whether microRNA profiles are associated with known prognostic factors in CLL.

METHODS

We evaluated the microRNA expression profiles of 94 samples of CLL cells for which the level of expression of 70-kD zeta-associated protein (ZAP-70), the mutational status of the rearranged immunoglobulin heavy-chain variable-region (IgV(H) ) gene, and the time from diagnosis to initial treatment were known. We also investigated the genomic sequence of 42 microRNA genes to identify abnormalities.

RESULTS

A unique microRNA expression signature composed of 13 genes (of 190 analyzed) differentiated cases of CLL with low levels of ZAP-70 expression from those with high levels and cases with unmutated IgV(H) from those with mutated IgV(H) . The same microRNA signature was also associated with the presence or absence of disease progression. We also identified a germ-line mutation in the miR-16-1-miR-15a primary precursor, which caused low levels of microRNA expression in vitro and in vivo and was associated with deletion of the normal allele. Germ-line or somatic mutations were found in 5 of 42 sequenced microRNAs in 11 of 75 patients with CLL, but no such mutations were found in 160 subjects without cancer (P<0.001).

CONCLUSIONS

A unique microRNA signature is associated with prognostic factors and disease progression in CLL. Mutations in microRNA transcripts are common and may have functional importance.

MicroRNA profiling reveals distinct signatures in B cell chronic lymphocytic leukemias

Little is known about the expression levels or function of micro-RNAs (miRNAs) in normal and neoplastic cells, although it is becoming clear that miRNAs play important roles in the regulation of gene expression during development [Ambros, V. (2003) Cell 113, 673-676; McManus, M. T. (2003) Semin. Cancer Biol. 13, 253-258]. We now report the genomewide expression profiling of miRNAs in human B cell chronic lymphocytic leukemia (CLL) by using a microarray containing hundreds of human precursor and mature miRNA oligonucleotide probes. This approach allowed us to identify significant differences in miRNome expression between CLL samples and normal CD5+ B cells; data were confirmed by Northern blot analyses and real-time RT-PCR. At least two distinct clusters of CLL samples can be identified that were associated with the presence or absence of Zap-70 expression, a predictor of early disease progression. Two miRNA signatures were associated with the presence or absence of mutations in the expressed Ig variableregion genes or with deletions at 13q14, respectively. These data suggest that miRNA expression patterns have relevance to the biological and clinical behavior of this leukemia.

A microRNA signature of hypoxia

Recent research has identified critical roles for microRNAs in a large number of cellular processes, including tumorigenic transformation. While significant progress has been made towards understanding the mechanisms of gene regulation by microRNAs, much less is known about factors affecting the expression of these noncoding transcripts. Here, we demonstrate for the first time a functional link between hypoxia, a well-documented tumor microenvironment factor, and microRNA expression. Microarray-based expression profiles revealed that a specific spectrum of microRNAs (including miR-23, -24, -26, -27, -103, -107, -181, -210, and -213) is induced in response to low oxygen, at least some via a hypoxia-inducible-factor-dependent mechanism. Select members of this group (miR-26, -107, and -210) decrease proapoptotic signaling in a hypoxic environment, suggesting an impact of these transcripts on tumor formation. Interestingly, the vast majority of hypoxia-induced microRNAs are also overexpressed in a variety of human tumors.

Extensive modulation of a set of microRNAs in primary glioblastoma

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles in animals and plants by repressing translation or cleaving RNA transcripts. The specific modulation of several microRNAs has been recently associated to some forms of human cancer, suggesting that these short molecules may represent a new class of genes involved in oncogenesis. In our study, we examined by microarray the global expression levels of 245 microRNAs in glioblastoma multiforme, the most frequent and malignant of primary brain tumors. The analysis of both glioblastoma tissues and glioblastoma cell lines allowed us to identify a group of microRNAs whose expression is significantly altered in this tumor. The most interesting results came from miR-221, strongly up-regulated in glioblastoma and from a set of brain-enriched miRNAs, miR-128, miR-181a, miR-181b, and miR-181c, which are down-regulated in glioblastoma.

An oligonucleotide microchip for genome-wide microRNA profiling in human and mouse tissues

MicroRNAs (miRNAs) are a class of small noncoding RNA genes recently found to be abnormally expressed in several types of cancer. Here, we describe a recently developed methodology for miRNA gene expression profiling based on the development of a microchip containing oligonucleotides corresponding to 245 miRNAs from human and mouse genomes. We used these microarrays to obtain highly reproducible results that revealed tissue-specific miRNA expression signatures, data that were confirmed by assessment of expression by Northern blots, real-time RT-PCR, and literature search. The microchip oligolibrary can be expanded to include an increasing number of miRNAs discovered in various species and is useful for the analysis of normal and disease states.

Cyclin G1 is a target of miR-122a, a microRNA frequently down-regulated in human hepatocellular carcinoma

We investigated the role of microRNAs (miRNAs) in the pathogenesis of human hepatocellular carcinoma (HCC). A genome-wide miRNA microarray was used to identify differentially expressed miRNAs in HCCs arisen on cirrhotic livers. Thirty-five miRNAs were identified. Several of these miRNAs were previously found deregulated in other human cancers, such as members of the let-7 family, mir-221, and mir-145. In addition, the hepato-specific miR-122a was found down-regulated in approximately 70% of HCCs and in all HCC-derived cell lines. Microarray data for let-7a, mir-221, and mir-122a were validated by Northern blot and real-time PCR analysis. Understanding the contribution of deregulated miRNAs to cancer requires the identification of gene targets. Here, we show that miR-122a can modulate cyclin G1 expression in HCC-derived cell lines and an inverse correlation between miR-122a and cyclin G1 expression exists in primary liver carcinomas. These results indicate that cyclin G1 is a target of miR-122a and expand our knowledge of the molecular alterations involved in HCC pathogenesis and of the role of miRNAs in human cancer.

Ultraconserved regions encoding ncRNAs are altered in human leukemias and carcinomas

Noncoding RNA (ncRNA) transcripts are thought to be involved in human tumorigenesis. We report that a large fraction of genomic ultraconserved regions (UCRs) encode a particular set of ncRNAs whose expression is altered in human cancers. Genome-wide profiling revealed that UCRs have distinct signatures in human leukemias and carcinomas. UCRs are frequently located at fragile sites and genomic regions involved in cancers. We identified certain UCRs whose expression may be regulated by microRNAs abnormally expressed in human chronic lymphocytic leukemia, and we proved that the inhibition of an overexpressed UCR induces apoptosis in colon cancer cells. Our findings argue that ncRNAs and interaction between noncoding genes are involved in tumorigenesis to a greater extent than previously thought.

CCAT2, a novel noncoding RNA mapping to 8q24, underlies metastatic progression and chromosomal instability in colon cancer

The functional roles of SNPs within the 8q24 gene desert in the cancer phenotype are not yet well understood. Here, we report that CCAT2, a novel long noncoding RNA transcript (lncRNA) encompassing the rs6983267 SNP, is highly overexpressed in microsatellite-stable colorectal cancer and promotes tumor growth, metastasis, and chromosomal instability. We demonstrate that MYC, miR-17-5p, and miR-20a are up-regulated by CCAT2 through TCF7L2-mediated transcriptional regulation. We further identify the physical interaction between CCAT2 and TCF7L2 resulting in an enhancement of WNT signaling activity. We show that CCAT2 is itself a WNT downstream target, which suggests the existence of a feedback loop. Finally, we demonstrate that the SNP status affects CCAT2 expression and the risk allele G produces more CCAT2 transcript. Our results support a new mechanism of MYC and WNT regulation by the novel lncRNA CCAT2 in colorectal cancer pathogenesis, and provide an alternative explanation of the SNP-conferred cancer risk.

Micro-RNA profiling in kidney and bladder cancers

OBJECTIVES

Micro-RNAs are a group of small noncoding RNAs with modulator activity of gene expression. Recently, micro-RNA genes were found abnormally expressed in several types of cancers. To study the role of the micro-RNAs in human kidney and bladder cancer, we analyzed the expression profile of 245 micro-RNAs in kidney and bladder primary tumors.

METHODS AND MATERIALS

A total of 27 kidney specimens (20 carcinomas, 4 benign renal tumors, and 3 normal parenchyma) and 27 bladder specimens (25 urothelial carcinomas and 2 normal mucosa) were included in the study. Total RNA was used for hybridization on an oligonucleotide microchip for micro-RNA profiling developed in our laboratories. This microchip contains 368 probes in triplicate, corresponding to 245 human and mouse micro-RNA genes.

RESULTS

A set of 4 human micro-RNAs (miR-28, miR-185, miR-27, and let-7f-2) were found significantly up-regulated in renal cell carcinoma (P < 0.05) compared to normal kidney. Human micro-RNAs miR-223, miR-26b, miR-221, miR-103-1, miR-185, miR-23b, miR-203, miR-17-5p, miR-23a, and miR-205 were significantly up-regulated in bladder cancers (P < 0.05) compared to normal bladder mucosa. Of the kidney cancers studied, there was no differential micro-RNA expression across various stages, whereas with increasing tumor-nodes-metastasis staging in bladder cancer, miR-26b showed a moderate decreasing trend (P = 0.082).

CONCLUSIONS

Our results show that different micro-RNAs are deregulated in kidney and bladder cancer, suggesting the involvement of these genes in the development and progression of these malignancies. Further studies are needed to clarify the role of micro-RNAs in neoplastic transformation and to test the potential clinical usefulness of micro-RNAs microarrays as diagnostic and prognostic tool.

MicroRNA deregulation in human thyroid papillary carcinomas

MicroRNAs (miRNAs) are a class of small non-coding RNAs involved in a wide range of basic processes such as cell proliferation, development, apoptosis and stress response. It has recently been found that they are also abnormally expressed in many types of human cancer. We analyzed the genome-wide miRNA expression profile in human thyroid papillary carcinomas (PTCs) using a microarray (miRNACHIP microarray) containing hundreds of human precursor and mature miRNA oligonucleotide probes. Using this approach, we found an aberrant miRNA expression profile that clearly differentiates PTCs from normal thyroid tissues. In particular, a significant increase in miRNA (miR)-221, -222 and -181b was detected in PTCs in comparison with normal thyroid tissue. These results were further confirmed by northern blot and quantitative RT-PCR analyses. Moreover, RT-PCR revealed miR-221, -222 and -181b overexpression in fine needle aspiration biopsies corresponding to thyroid nodules, which were eventually diagnosed as papillary carcinomas after surgery. Finally, miR-221, -222 and -181b overexpression was also demonstrated in transformed rat thyroid cell lines and in mouse models of thyroid carcinogenesis. Functional studies, performed by blocking miR-221 function and by overexpressing miR-221 in human PTC-derived cell lines, suggest a critical role of miR-221 overexpression in thyroid carcinogenesis. In conclusion, these data, taken together, indicate an miRNA signature associated with PTCs, and suggest miRNA deregulation as an important event in thyroid cell transformation.

MiR-122/cyclin G1 interaction modulates p53 activity and affects doxorubicin sensitivity of human hepatocarcinoma cells

The identification of target genes is a key step for assessing the role of aberrantly expressed microRNAs (miRNA) in human cancer and for the further development of miRNA-based gene therapy. MiR-122 is a liver-specific miRNA accounting for 70% of the total miRNA population. Its down-regulation is a common feature of both human and mouse hepatocellular carcinoma (HCC). We have previously shown that miR-122 can regulate the expression of cyclin G1, whose high levels have been reported in several human cancers. We evaluated the role of miR-122 and cyclin G1 expression in hepatocarcinogenesis and in response to treatment with doxorubicin and their relevance on survival and time to recurrence (TTR) of HCC patients. We proved that, by modulating cyclin G1, miR-122 influences p53 protein stability and transcriptional activity and reduces invasion capability of HCC-derived cell lines. In addition, in a therapeutic perspective, we assayed the effects of a restored miR-122 expression in triggering doxorubicin-induced apoptosis and we proved that miR-122, as well as cyclin G1 silencing, increases sensitivity to doxorubicin challenge. In patients resected for HCC, lower miR-122 levels were associated with a shorter TTR, whereas higher cyclin G1 expression was related to a lower survival, suggesting that miR-122 might represent an effective molecular target for HCC. Our findings establish a basis toward the development of combined chemo- and miRNA-based therapy for HCC treatment.

Specific microRNAs are downregulated in human thyroid anaplastic carcinomas

Thyroid carcinomas comprise a broad spectrum of tumors with different clinical behaviors. On the one side, there are occult papillary carcinomas (PTC), slow growing and clinically silent, and on the other side, rapidly growing anaplastic carcinomas (ATC), which are among the most lethal human neoplasms. We have analysed the microRNA (miR) profile of ATC in comparison to the normal thyroid using a microarray (miRNACHIP microarray). By this approach, we found an aberrant miR expression profile that clearly differentiates ATC from normal thyroid tissues and from PTC analysed in previous studies. In particular, a significant decrease in miR-30d, miR-125b, miR-26a and miR-30a-5p was detected in ATC in comparison to normal thyroid tissue. These results were further confirmed by northern blots, quantitative reverse transcription-PCR analyses and in situ hybridization. The overexpression of these four miRs in two human ATC-derived cell lines suggests a critical role of miR-125b and miR-26a downregulation in thyroid carcinogenesis, since a cell growth inhibition was achieved. Conversely, no effect on cell growth was observed after the overexpression of miR-30d and miR-30a-5p in the same cells. In conclusion, these data indicate a miR signature associated with ATC and suggest the miR deregulation as an important event in thyroid cell transformation.

MicroRNA-221 targets Bmf in hepatocellular carcinoma and correlates with tumor multifocality

Deregulated cell proliferation and apoptosis play a major role in hepatocellular carcinoma (HCC). MicroRNAs participate in the modulation of key molecules linked to hepatocarcinogenesis.

PURPOSE

This study aims to investigate the role of miR-221 in the modulation of Bmf, a proapoptotic BH3-only protein, and to characterize miR-221 contribution to hepatocarcinogenesis through modulation of apoptosis.

EXPERIMENTAL DESIGN

Transfection of miR-221 and anti-miR-221 in HCC-derived cell lines and luciferase reporter assay were used to assess Bmf as a target of miR-221. Modulation of miR-221 and Bmf expression contributed to characterize their role in anoikis. Primary HCC tissues were analyzed to assess the clinical relevance of in vitro findings.

RESULTS

Enforced miR-221 expression caused Bmf down-regulation, whereas anti-miR-221 induced its up-regulation. A luciferase reporter assay confirmed Bmf as a target of miR-221. Following matrix detachment, miR-221 silencing led to increased apoptotic cell death. The analysis of HCC tissues revealed an inverse correlation between miR-221 and Bmf expression and a direct correlation between Bmf and activated caspase-3, as a marker of apoptosis. High miR-221 levels were associated with tumor multifocality and reduced time to recurrence after surgery.

CONCLUSIONS

Our results indicate that miR-221, by targeting Bmf, inhibits apoptosis. Moreover, in HCC, miR-221 overexpression is associated with a more aggressive phenotype. These findings, together with the previously reported modulation of CDKN1B/p27 and CDKN1C/p57, show that miR-221 simultaneously affects multiple pro-oncogenic pathways and suggest miR-221 as a potential target for nonconventional treatment against HCC.

MicroRNA fingerprints identify miR-150 as a plasma prognostic marker in patients with sepsis

BACKGROUND

The physiopathology of sepsis continues to be poorly understood, and despite recent advances in its management, sepsis is still a life-threatening condition with a poor outcome. If new diagnostic markers related to sepsis pathogenesis will be identified, new specific therapies might be developed and mortality reduced. Small regulatory non-coding RNAs, microRNAs (miRNAs), were recently linked to various diseases; the aim of our prospective study was to identify miRNAs that can differentiate patients with early-stage sepsis from healthy controls and to determine if miRNA levels correlate with the severity assessed by the Sequential Organ Failure Assessment (SOFA) score.

METHODOLOGY/PRINCIPAL FINDINGS

By using genome-wide miRNA profiling by microarray in peripheral blood leukocytes, we found that miR-150, miR-182, miR-342-5p, and miR-486 expression profiles differentiated sepsis patients from healthy controls. We also proved by quantitative reverse transcription-polymerase chain reaction that miR-150 levels were significantly reduced in plasma samples of sepsis patients and correlated with the level of disease severity measured by the SOFA score, but were independent of the white blood counts (WBC). We found that plasma levels of tumor necrosis factor alpha, interleukin-10, and interleukin-18, all genes with sequence complementarity to miR-150, were negatively correlated with the plasma levels of this miRNA. Furthermore, we identified that the plasma levels ratio for miR-150/interleukin-18 can be used for assessing the severity of the sepsis.

CONCLUSIONS/SIGNIFICANCE

We propose that miR-150 levels in both leukocytes and plasma correlate with the aggressiveness of sepsis and can be used as a marker of early sepsis. Furthermore, we envision miR-150 restoration as a future therapeutic option in sepsis patients.

Non-coding RNAs in disease: from mechanisms to therapeutics

Non-coding RNAs (ncRNAs) are a heterogeneous group of transcripts that, by definition, are not translated into proteins. Since their discovery, ncRNAs have emerged as important regulators of multiple biological functions across a range of cell types and tissues, and their dysregulation has been implicated in disease. Notably, much research has focused on the link between microRNAs (miRNAs) and human cancers, although other ncRNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are also emerging as relevant contributors to human disease. In this Review, we summarize our current understanding of the roles of miRNAs, lncRNAs and circRNAs in cancer and other major human diseases, notably cardiovascular, neurological and infectious diseases. Further, we discuss the potential use of ncRNAs as biomarkers of disease and as therapeutic targets.

mRNA/microRNA gene expression profile in microsatellite unstable colorectal cancer

Background

Colorectal cancer develops through two main genetic instability pathways characterized by distinct pathologic features and clinical outcome.

Results

We investigated colon cancer samples (23 characterized by microsatellite stability, MSS, and 16 by high microsatellite instability, MSI-H) for genome-wide expression of microRNA (miRNA) and mRNA. Based on combined miRNA and mRNA gene expression, a molecular signature consisting of twenty seven differentially expressed genes, inclusive of 8 miRNAs, could correctly distinguish MSI-H versus MSS colon cancer samples. Among the differentially expressed miRNAs, various members of the oncogenic miR-17-92 family were significantly up-regulated in MSS cancers. The majority of protein coding genes were also up-regulated in MSS cancers. Their functional classification revealed that they were most frequently associated with cell cycle, DNA replication, recombination, repair, gastrointestinal disease and immune response.

Conclusion

This is the first report that indicates the existence of differences in miRNA expression between MSS versus MSI-H colorectal cancers. In addition, the work suggests that the combination of mRNA/miRNA expression signatures may represent a general approach for improving bio-molecular classification of human cancer.

Micromarkers: miRNAs in cancer diagnosis and prognosis

Molecular diagnostics in cancer should provide the highest specificity and sensitivity in classification, prognostic stratification and early detection. miRNAs could contribute to hitting the mark, or at least to come nearer, by virtue of their cancer-specific expression and stability. Indeed, different to other RNA classes, miRNAs can be detected and quantified not only in frozen tissues, but also in formalin-fixed paraffin-embedded tissues, as well as serum/plasma samples. Thus, miRNA studies have quickly moved from research on the molecular basis of cancer to areas of clinical application. This review summarizes the potential role of miRNAs as molecular markers for cancer classification, prognostic stratification and drug-response prediction. It also summarizes their potential as circulating markers and cancer-predisposing genes. If we consider that studies on miRNAs in cancer therapy have already given important contributions, miRNAs have an impact in all cancer areas. Whether this will translate into clinical applications is still too early to say. However, in the diagnostic field, miRNAs may already represent an improvement over presently available approaches; for example, their expression profile is effective in the identification of tissue of origin of metastasis. In addition, circulating miRNAs are expected to provide improved specificity and/or sensitivity over presently available markers.

Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD

An inflammatory component is present in the microenvironment of most neoplastic tissues, including those not causally related to an obvious inflammatory process. Several microRNAs, and especially miR-155, play an essential role in both the innate and adaptative immune response. Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural antioxidant with anti-inflammatory properties that is currently at the stage of preclinical studies for human cancer prevention. Here, we establish that, in human THP-1 monocytic cells as well as in human blood monocytes, resveratrol upregulates miR-663, a microRNA potentially targeting multiple genes implicated in the immune response. In THP-1 cells, miR-663 decreases endogenous activator protein-1 (AP-1) activity and impairs its upregulation by lipopolysaccharides (LPS), at least in part by directly targeting JunB and JunD transcripts. We further establish that the downregulation of AP-1 activity by resveratrol is miR-663 dependent and that the effects of resveratrol on both AP-1 activity and JunB levels are dose dependent. Finally, we show that resveratrol impairs the upregulation of miR-155 by LPS in a miR-663-dependent manner. Given the role of miR-155 in the innate immune response and the fact that it is upregulated in many cancers, our results suggest that manipulating miR-663 levels may help to optimize the use of resveratrol as both an anti-inflammatory and anticancer agent against malignancies associated with high levels of miR-155.

Oncogenic role of miR-483-3p at the IGF2/483 locus

hsa-mir-483 is located within intron 2 of the IGF2 locus. We found that the mature microRNA (miRNA) miR-483-3p is overexpressed in 100% of Wilms' tumors. In addition, colon, breast, and liver cancers exhibit high or even extremely high levels of miR-483-3p in approximately 30% of the cases. A coregulation with IGF2 mRNA was detected, although some tumors exhibited high expression of miR-483-3p without a concomitant increase of IGF2. These findings suggested that miR-483-3p could cooperate with IGF2 or act as an autonomous oncogene. Indeed, here we prove that an anti-miRNA oligonucleotide against miR-483-3p could inhibit the miRNAs without affecting IGF2 mRNA and it could suppress tumorigenicity of HepG2 cells, a cell line that overexpresses miR-483-3p and IGF2. Conversely, no antitumor effect was elicited by inhibition of IGF2. The oncogenic mechanism of miR-483-3p was at least partially clarified by the finding that it could modulate the proapoptotic protein BBC3/PUMA and miR-483-3p enforced expression could protect cells from apoptosis. Our results indicate that miR-483-3p could function as an antiapoptotic oncogene in various human cancers and reveal a new, potentially important target for anticancer therapy.

MicroRNAs in human cancer: from research to therapy

Numerous miRNAs are deregulated in human cancers, and experimental evidence indicates that they can play roles as oncogenes or tumor suppressor genes. Similarly to cancer genes that encode proteins, deregulation of miRNA-encoding genes is associated with genetic or epigenetic alterations, such as deletions, amplifications, point mutations and aberrant DNA methylation. The discovery that miRNAs interact with known oncogenes has established further links with molecular pathways implicated in malignant transformation. Finally, miRNAs can be used as diagnostic markers, and their potential as therapeutic molecules has moved miRNAs from the area of basic research to the field of cancer biotechnology.

Identification of differentially expressed microRNAs by microarray: a possible role for microRNA genes in pituitary adenomas

MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by targeting mRNA. It has been demonstrated that miRNA expression is altered in many human cancers, suggesting that they may play a role in human neoplasia. To determine whether miRNA expression is altered in pituitary adenomas, we analyzed the entire miRNAome in 32 pituitary adenomas and in 6 normal pituitary samples by microarray and by Real-Time PCR. Here, we show that 30 miRNAs are differentially expressed between normal pituitary and pituitary adenomas. Moreover, 24 miRNAs were identified as a predictive signature of pituitary adenoma and 29 miRNAs were able to predict pituitary adenoma histotype. miRNA expression could differentiate micro- from macro-adenomas and treated from non-treated patient samples. Several of the identified miRNAs are involved in cell proliferation and apoptosis, suggesting that their deregulated expression may be involved in pituitary tumorigenesis. Predictive miRNAs could be potentially useful diagnostic markers, improving the classification of pituitary adenomas.